SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71f1517fa1cd71d6857cc76f25ca1b94660cd23cd15a02943c0f9d84f268dd88' 
  AND token = 'kCf2wXv5KnIyx7hPZLyfvmLfrYUyGQ+kxZr08f9CHBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}